I've never stacked chicken thighs---I just use a bigger pan when needed...If that is not an option for you then just give it a try....You may want to consider cooking at a slightly higher temperature (375*) and for a little longer period of time 35-40 minutes...Turning the meat once during the cook time may help them all cook more evenly also...

Good Luck and Have Fun!!

__________________There is only one Quality worse than Hardness of Heart, and that is Softness of Head.